1. Field of the Invention
The present invention relates to a sheet-shaped laminated structure that is made of a thermoplastic resin and excellent in gracefulness and design, and use thereof. More specifically, it relates to a sheet-shaped laminated structure that shows a continuous change in color tone along a sheet surface when viewed from an outside, and use thereof.
2. Prior Art
In recent years, product designs for increasing the value of a product, particularly, highly elaborative designs of molded articles made of resins are demanded. Among them is an improvement of a design by a continuous change in color tone (gradation coloring). As one method for improving a design, there is employed a molding method in which a film or sheet having a print, etc., of a gradation pattern is placed in a mold beforehand and a resin is injection-molded, such as an insert molding method. However, this method requires a number of steps of preparing a sheet, printing, trimming, and the like, and it cannot be said that the method is fully attractive with regard to a design.
JP-A-53-83884 or JP-A-56-123235 proposes a container having an inner layer and an outer layer varied in thickness, the outer layer being composed of a resin containing a colorant, and having a color in gradation in a vertical direction, and a molding method therefor. In the molded article (container) obtained by the method described in each of the above publications, however, the direction of gradation of the color is vertical in constitution, and it is limited to a container having an upper or lower portion densely colored or having a relatively simple color-tone. Further, the above method has a difficulty in producing a molded article having a three-dimensional pattern (a letter, a character or a figure) formed in an interfacial portion of the layers.
As explained above, there has not been provided any relatively thick, plate-shaped laminated structure that has a high standard of design, which has a continuous color tone change that can be not only in one direction but also in multi-directions, and which can have a clear three-dimensional pattern in an interfacial portion of layers.
Problems to be Solved by the Invention
It is therefore a first object of the present invention to provide a sheet-shaped laminated structure that is excellent in gracefulness and design, has a continuous change in color tone and is composed of a plurality of layers formed of a thermoplastic resin.
It is a second object of the present invention to provide a sheet-shaped laminated structure that has a continuous change in color tone which change can be not only in one direction along a sheet surface but also in multi-directions and which permits a combination of a plurality of colors.
It is a third object of the present invention to provide a sheet-shaped laminated structure having a clear three-dimensional pattern such as a character (or letter) or a figure on a sheet surface having a continuous change in color tone.
It is another object of the present invention to provide a sheet-shaped laminated structure that has a thickness sufficient for retaining a form, which is transparent or semi-transparent and has a continuous change in color tone.
It is a further another object of the present invention to provide a sheet-shaped laminated structure that has practical strength for advantageous use as a decorative glass window, an interior decoration member, a glass window for a display case, a partition, a door, a window glass for an automobile, an outer plate of an automobile, a lamp cover, an ornament, an instrumental panel or center panel for an automobile, an interior or exterior decoration lace and a garnish for an automobile, a display device, a display board, a light guide plate, a beacon plate, a windshield plate, a roof material, furniture, a housing member for various office automation machines such as a computer and a portable terminal, a housing member for various electric machines such as a cellular phone and a portable audio device, an illumination panel for a slot machine, etc., and a material for miscellaneous goods.
It is still further another object of the present invention to provide a highly elaborately designed illuminator that utilizes a continuous change in transparent or semi-transparent color tone.
Means to Solve the Problems
According to studies made by the present inventors, the above objects of the present invention can be achieved by a highly elaborately designed sheet-shaped laminated structure wherein:
(1) the sheet-shaped laminated structure is a sheet-shaped laminated structure composed of at least two layers formed of a thermoplastic resin each,
(2) at least one outer layer forming a surface of said laminated structure is a layer (B) formed of a transparent resin,
(3) at least one layer composing said laminated structure contains a dye, a pigment or a light diffusing agent and has a monotonous thickness change at least in one direction of a sheet surface of the laminated structure, and
(4) said laminated structure shows a continuous change in color tone along the sheet surface when visually observed toward an outer surface of the layer (B) formed of a transparent resin.
The laminated structure of the present invention will be explained in detail hereinafter.
The laminated structure of the present invention includes many embodiments of combinations depending upon number of layers, forms of each layer, coloring or non-coloring of each layer, or kinds of colors, and further, the laminated structure shows a change in gracefulness and a design depending upon directions in which the laminated structure is visually observed and directions in which a light source is placed. While these are sources that exhibit the features and advantages of the laminated structure of the present invention, the laminated structure of the present invention will be explained with reference to drawings for an understanding thereof.